- 4 tablespoons olive oil
- 1 pound button or cremini mushrooms, stems removed and reserved, caps sliced
- ½ pound oyster mushrooms, stems removed and reserved, caps sliced
- ½ pound shiitake or porcini mushrooms, stems removed and reserved, caps sliced
- 8 cups mineral or filtered water
- ½ cup white port or white wine
- 1 large Spanish onion, chopped
- 2 celery stalks, chopped
- 2 leeks, rinsed well and chopped
- 3 garlic cloves, minced
- 10 fresh thyme stems, leaves chopped and stems reserved
- 2 teaspoons dried rosemary
- 2 bay leaves
- ½ teaspoon ground black pepper
- ½ pound cranberry or Borlotti beans, rinsed and picked over to remove debris
- 1 (28-ounce) can whole tomatoes, drained and diced
- 1 bunch kale, chopped
- 1 tablespoon balsamic vinegar
- 2 teaspoons kosher salt
- Heat 2 tablespoons of the oil in a large stockpot over medium heat. Add the mushroom stems and a few button mushroom caps and sweat for 5 minutes, until tender and releasing juice. Add the water and white port and bring the mixture to a boil. Reduce the heat, partially cover, and simmer for 20 minutes. Strain the stock through a fine sieve to remove solids, reserving 5 cups of the liquid; set aside.
- Heat the remaining 2 tablespoons of the oil in a large stockpot over medium heat. Add the onion, celery, leeks, and 2 cloves of the garlic and sweat for 4 minutes, until tender.
- Tie the thyme stems together with string and add to the pot with the rosemary, bay leaves, and pepper. Stir to coat the vegetables.
- Add the mushrooms and sauté 5 minutes.
- Add the reserved mushroom liquid, beans, and tomatoes. Bring the mixture to a boil, reduce heat, partially cover, and simmer for 2 hours, until the beans are tender.
- Remove from the heat and stir in the kale, balsamic vinegar, chopped thyme, salt, and remaining garlic clove. Cover and let steep 1 minute.
- To serve, remove the thyme stems and bay leaves and ladle the soup into bowls.